Magnetic read head signal preamplifiers used in hard disk drives typically require fast recovery from electronic transients such as power switching, write to read switching, and thermal asperity. If the preamplifier is unable to recover quickly from transients, then performance of the hard disk drive may be compromised. Power switching occurs when the power is turned on or off. Write to read switching occurs when the disk drive changes functions from writing to the hard disk to reading from the hard disk. A transient such as thermal asperity occurs when a disk drive head hits the disk as the disk goes by. The contact with the disk causes heat on the disk drive head and this heat may show up as a voltage. A thermal asperity may generate a significant amount of energy and only a small fraction of that energy should be processed. These examples of electronic transients typically produce signals that are undesirable to process. If these electronic transients are processed, performance is typically reduced.
Fast recovery from electronic transients, such as power switching, write to read switching, and thermal asperity, is typically achieved via a complicated circuit performing complicated functions, such as dual peak detection and subtraction. Conventional preamplifier circuits that provide fast recovery from transients typically require a substantially large number of components. A large number of circuit devices potentially increase the risk of a device failure in addition to increasing the cost of the circuit.
It would be desirable to allow preamplifiers to quickly recover from electrical transients by integrating a simple circuit. The present invention addresses such a need.